 |
 |
Water Bridge and Weight
Name: Aal
Status: Other
Grade: Other
Location: NJ
Country: United States
Date: November 2007
Question:
When designing a water bridge, does the
bridge have to be designed to withstand the
additional weight of ship and barge traffic, or just
the weight of the water?
Replies:
Hi Aal,
In a water bridge, such as the amazing one that was recently
opened in Germany shown in the photo here...
http://www.funonthenet.in/content/view/223/31/
...the bridge only needs to withstand the weight of the
water. This is because when a boat floats on water, it
displaces its own weight of water. That means, that the
volume of water that the hull replaces, weighs exactly as
much as the boat does. The water that the hull displaces, is
replaced by a boat that weighs exactly as much as the water
used to.
Regards,
Bob Wilson
The simple answer is that no, a ship will simply displace its own weight of
water and no extra weight needs to be supported by the bridge.
Engineering structures are designed typically with many other considerations
in mind besides the normal weight to be carried. For example, structures
typically have a "safety factor." A safety factor of three, for example,
means that the structure will actually support three times the design load
without actually failing. Other important considerations for bridges (and
buildings) are wind loading and earthquakes. So a full answer to this
question would require the expertise of a civil engineer familiar with such
projects.
Robert Erck
Click here to return to the Engineering Archives
| |
Update: June 2012
|
|
